EE vs IA - what's the diff?

IA and EE overlap is usually addressed in the EE subject report and the biology subject reports.

2018 EE Bio subject report says

Recommendations for the supervision of future candidates Candidate are in need of ongoing guidance about a number of issues: 

• The EE is not an IA and requires a different approach. The EE must be firmly based on published research and must integrate ideas and information gleaned from published sources into the argument. 

• Candidates (and supervisors) need to pay attention to the changes in the EE that are in place and be familiar with the current EE guide. 

• The best essays are school based laboratory studies that use a straightforward approach and present a clear well supported argument based on a significant body of data. 

• Candidates need guidance on how to reflect in a meaningful way, moving beyond simple descriptive reflection to more analytical and evaluative ideas.

2021 EE Bio subject report says

In other cases, essays are clearly and unduly aligned with the protocol for internal assessment. Practical investigations of this type do not score highly against B and C in particular. In the case of B not enough attention is placed on the knowledge surrounding the investigation as gleaned from the sources either in the introduction or the discussion. While this “IA” approach can lead to a strong assessment for some aspects of C (analysis in particular) critical evaluation is often confined to an assessment of the sources of experimental error and rarely addresses broader issues such as the overall research approach or the nature and selection process for the sources accessed.